What is the clitelum?

The clitelum, or clitellum, is a thickened, glandular region found in certain annelids, particularly earthworms. It plays a crucial role in reproduction by secreting a mucus ring that facilitates the formation of a cocoon for the fertilized eggs. The clitellum is typically visible as a swollen band around the body of the worm and is most prominent during the breeding season.